A Power Factor Correction (PFC) circuit is used for reducing the input harmonic current. However, the traditional PFC circuit has complicated techniques and design, and high component count, which makes it large in size and high in cost. So the design of the PFC circuit often makes a compromise between performance and cost.
In recent years, the studies of the one cycle control method for PFC focus on how to simplify the structure of the traditional control circuit for PFC, so as to avoid sampling the input voltage and eliminate the complicated analog multiplier. While the one cycle control circuit for PFC solves these problems very well. So far, one cycle control chips for PFC have been developed and applied, such as the one cycle control continuous conduction mode PFC boost converter integrated circuit with power switch and boost converter disclosed in Chinese patent No. 200380109048.6. Although one cycle control chips for PFC are simple and reliable, the cost-to-use is too high.
It is known that many systems are controlled by main control chips such as DSP. DSP and other main control chips have powerful capacity of software integration, compatibility and signal processing, so it will be an increase of cost and a waste of resources as well if a specific one cycle control chip for PFC is additionally applied in such system. For example, power factor correction techniques are applied broadly to the power supplies of compressor in the field of air conditioner, and a main control chip has been integrated in the main control board of the compressor, so it is necessary to develop corresponding techniques to avoid using specific high cost one cycle control chips for PFC.